Working with PDT source code in Eclipse

To comfortably edit PDT source code you will need Eclipse JDT and PDE. Ideally Eclipse Classic package from Eclipse downloads page is what you need.

Check out PDT plugins to Eclipse workspace. Select the XML text below and save it to file projectSet.psf

In Eclipse, choose File->Import, select Team->Team Project Set and choose projectSet.psf file created in step 2. After finishing the import wizard, you should see all PDT source code in your workspace. Source code might not be compiling yet

Find file org.eclipse.php.core/Resources/parserTools/build.xml and launch it as Ant Build. This will generate PHP language parser classes.